Efficiency monitoring for the user of large rotating machines, such as motors or turbines has become increasingly important because of the increased cost of energy. One technique for monitoring efficiency is a torque sensor which, when coupled with revolutions per minute (RPM), measures transferred energy from the prime mover to a load such as a compressor or pump.
Since the torque measuring instrumentation in the form of, for example, a strain gauge on the shaft is on a rotating member it is necessary to provide some type of telemetering such as radio, light or mechanical transfer techniques such as slip rings, or electrical induction techniques. These are all known and the major problem in this area is to provide, in view of the very stringent ambient conditions, a reliable telemetry system which is low cost, durable and error-free in transmitting data. It is also desirable to have a system which is flexible in that many different types of data sources (such as strain gauge and semiconductor devices) may be used and where the system can accommodate all of these different data sources at the same time.